Business-quality video conferencing systems are currently implemented either as a standalone appliance or integrated into a host unit. The standalone appliance implementation, for example a set-top box, can be connected to a television set, but its functionality is in general limited to sending video and audio and receiving video and audio. In contrast, a video conferencing system integrated into a computer has access to other applications running on the computer and therefore has the potential for incorporating data from those applications into the video and audio stream, thereby combining video conferencing with application sharing.
Computer-based video conferencing systems that are implemented solely in software are commercially available, for example, “CU-SeeMe” from White Pine Software Inc. of Nashua, N.H., USA. Such software-only systems rely on the computer's standard video card to interface to the video camera (“video grabbing”) and computer monitor, and do all of the video encoding and decoding on the host computer's central processing unit (CPU), thus resulting in a less than business quality of video conferencing.
Business quality computer-based video conferencing systems are currently implemented by an add-on card that is inserted into an empty slot in the internal input/output bus of the computer (for example, a PCI card in the case of an Intel-based computer). The video camera and microphone are connected to the add-on card, which has dedicated hardware for video grabbing, dedicated hardware for video and audio encoding and decoding, and dedicated hardware for multiplexing of the video and audio streams. The system also includes at least one installable software application for coordinating a video conference. Such systems include “Cruiser 150” from VCON Ltd. of Herzliya, Israel and “OnWAN340” from Zydacron Inc. of Manchester, N.H., USA.
One of the disadvantages of such a system is that the installation of the add-on card is a cumbersome and daunting task, requiring one to open the personal computer or workstation. Another disadvantage is that there is no support for laptops. Yet another disadvantage is that all of the video processing is done on the card and none on the computer's CPU, resulting in a load imbalance due to not fully utilizing the processing power of the CPU. A further disadvantage is that there may be a conflict with other cards that are installed on the computer's internal bus due to overlapping in resource definitions.
It would therefore be beneficial to have a multimedia communication system that is easily installable and enables application sharing with a host such as a personal computer, workstation or laptop. It would also be beneficial for the system to provide business quality video conferencing while exploiting the processing power of the host's CPU.
Universal Serial Bus (USB) cameras connected to personal computers are commercially available. “USBvision II NT1004” from Nogatech Ltd. of Kfar Saba, Israel is a commercially available chipset for compressing video grabbed by a USB camera for locally viewing the video on the personal computer. However, the compression performed by “USBvision II NT1004” or an equivalent product is unsuitable for transferring the video over bandwidth limited communication media such as IP networks and ISDN lines. A video conferencing system based on such a product would have to decompress the video at the host computer and compress it again using a standard multimedia communication format such as MPEG4, ITU H.263 or ITU G.723 before transferring the video to a remote computer. This decompression and recompression at the host computer would generate additional computational load and would degrade the quality of the perceived video at the remote computer.